A heat pump water heater has been widely used because of its advantages of energy saving, environmental protection and safety. A heat pump special compressor uses two kinds of refrigerants of an R22 and an R407C, wherein the R407C of refrigerant is an eco-friendly refrigerant. According to “Montreal Protocol”, the R22 is taken as a HCFC of working substance and is the second batch of substance to be replaced. The fourth meeting of States Parties of “Protocol” held in Copenhagen, Denmark in 1992 has decided to advance the disable time of the R22 to be 2020; hence it has become increasingly close that the refrigeration system uses environmentally friendly alternative refrigerants. The R407C of the refrigerant, as an important alternative of R22 refrigerant, is a mixed working substance and a non-azeotropic mixture of an R125, an R32 and an R134a (25/23/52% by weight percentage) with temperature glide of 7K. The temperature glide is the change value of the phase transition temperature of the mixture of the refrigerants when the phase transition of the mixture occurs under the constant pressure. As to the non-azeotropic mixed refrigerant, its phase change temperature will greatly vary during the phase transition process. Therefore, a heat exchanger shall be optimized; otherwise the temperature glide will have a serious impact on the refrigeration of a device. The R407C of the environmentally friendly refrigerant is a long-term alternative of the R22 in some applications. After the R22 of an equipment with a tube-and-shell-type heat exchanger and of the prior condenser and the prior evaporator is directly converted into the R407C of the refrigerant, the surface heat transfer coefficient will be relatively low, resulting in changes of heat exchange performance and the changes of the status of the thermodynamic cycle of a system; therefore, it is very important to re-research the technology of the system using the R407C of the refrigerant Chinese utility model patent of “a refrigerant cycle device of an R407C of a refrigerant environmentally friendly industrial chiller” (Chinese utility model patent No.: ZL 200820301799.8, Authorized Public No.: CN201281485Y) discloses the refrigerant cycle device of the R407C of the refrigerant environmentally friendly industrial chiller, including a condensing heat exchanger connected with external cooling water through inlet and outlet pipes, a compressors and an evaporation heat exchanger connected with external water to be cooled through the inlet and outlet pipes. The three all form a closed loop through pipe connection, being characterized in that: The evaporation heat exchanger is a plate-type evaporator absorbing the heat from the cooled water through the evaporation of the R407C of the refrigerant. The flow direction of the cooled water therein is opposite to that of the R407C of the refrigerant and forms whole countercurrent heat exchange. The condensing heat exchanger releases the heat to the plate-type condenser of the cooled water through the condensation of the R407C of the refrigerant. The flow direction of the cooled water therein is opposite to that of the R407C of the refrigerant and forms whole countercurrent heat exchange. Hence, a refrigerant circulating system effectively prevents the temperature glide from significantly affecting the heat exchange amount of the heat exchange when the R407C of the refrigerant condenses and evaporates and avoid imbalance of a system. The utility model is applied to an industrial chiller which meets the CFC-free environmentally friendly requirements and uses the alternative environmentally friendly refrigerant of the R407C as the refrigerant, which has stable and reliable heat transfer characteristics. Chinese invention patent application of “an air conditioning heat exchanger with a mixed refrigerant and an air conditioner” (Chinese Patent Application No.: 201210036236.1, Publication Number: CN 102538308A) discloses the air conditioning heat exchanger with the mixed refrigerant and the air conditioner, comprising a finned pipe heat exchanger, a manifold pipe, at least two ways of splitting pipes and a shunt connecting the manifold pipe and every the splitting pipe. The manifold pipe is connected with an inlet end of the shunt. A shunt outlet of the shunt is respectively connected with one end of each of the splitting pipe, and the other end of the splitting pipe is respectively connected with a pipeline on the heat exchanger of a finned pipe, so as to solve the problem of the temperature glide of the mixed refrigerant because of non-azeotropy, and improve the efficiency and the heating capacity of the heat exchanger of the air conditioner. Although the above utility model and the invention respectively propose the different technical solutions solving the problem of the temperature glide of the mixed refrigerant, the technical solution in the prior art adapts to the temperature glide of the mixed refrigerant by controlling the temperature of the heat exchanger, which does not fundamentally solve the problem of the imbalance of the phase change process caused by the non-isothermal characteristic of the phase change of the R407C of the non-azeotropic mixed working substance.